Try by this way
using (var library = new MediaLibrary())
{
var savedPictures = library.Pictures.ToList();
if (savedPictures.Any())
{
foreach (var pic in savedPictures)
{
var bitmap = new WriteableBitmap(pic.Width, pic.Height);
using (var stream = pic.GetImage()) //here you will get the stream
{
bitmap.SetSource(stream);
}
}
}
}